IB Biology HL D1.1.5 Applications Questions
Explore STR and gel-band evidence, PCR-supported profiling and justified paternity or forensic conclusions in IB Biology HL D1.1.5.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Exam points
- Analyse STR repeat numbers and gel-band patterns to support or reject a paternity or forensic match.
- Evaluate a DNA-profile conclusion by checking that all child bands are inherited from the parents or that crime-scene bands match the suspect.
- Explain medical applications of PCR, including viral-strain identification, genetic testing, tissue typing or vaccine development.
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IB Biology HL D1.1.5 Applications Questions question 1
[Maximum number: 5]
Describe how DNA profiling can be used to establish paternity.
DNA sample is collected from the child and its (potential) parents;
from saliva/mouth swab/blood/other body cells;
PCR used to amplify/produce more copies of the DNA;
short tandem repeats/genes consisting of a repeating sequence of bases repeats copied/used;
number of repeats varies between individuals;
unlikely that two individuals have same number of repeats for every gene included;
gel electrophoresis used to separate DNA fragments according to length/number of repeats;
gel electrophoresis generates a unique pattern of bands
DNA profile is the pattern of bands / diagram showing pattern of bands as in a DNA profile;
all bands in the child's profile must be in one of the parents' profiles;
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